:root {
  --bg: #ffffff;
  --fg: #1d1d1f;
  --fg-soft: #6e6e73;
  --border: rgba(0, 0, 0, 0.1);
  --soft: #f5f5f7;
  --accent: #4a4fd4;
  --on-accent: #ffffff;
  --shadow: 0 10px 30px rgba(0, 0, 0, 0.1);
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #0b0b0d;
    --fg: #f5f5f7;
    --fg-soft: #a1a1a6;
    --border: rgba(255, 255, 255, 0.12);
    --soft: #151517;
    --accent: #a8abff;
    --on-accent: #0b0b0d;
    --shadow: 0 12px 34px rgba(0, 0, 0, 0.55);
  }
}

*,
*::before,
*::after {
  box-sizing: border-box;
}

html,
body {
  margin: 0;
  height: 100%;
}

body {
  background: var(--bg);
  color: var(--fg);
  font-family: -apple-system, BlinkMacSystemFont, "SF Pro Text", "Segoe UI", Roboto,
    "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  -webkit-font-smoothing: antialiased;
  -webkit-tap-highlight-color: transparent;
  overscroll-behavior: none;
}

.app {
  display: flex;
  flex-direction: column;
  min-height: 100%;
  padding: env(safe-area-inset-top) env(safe-area-inset-right) env(safe-area-inset-bottom)
    env(safe-area-inset-left);
}

.topbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  padding: 0.9rem 1.25rem;
  border-bottom: 1px solid var(--border);
}

.brand {
  color: var(--fg-soft);
  font-size: 0.9rem;
  text-decoration: none;
}

.title {
  font-size: 0.98rem;
  font-weight: 600;
  letter-spacing: -0.01em;
}

main {
  flex: 1;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  padding: 1.75rem 1.25rem 2rem;
}

.screen {
  width: 100%;
  display: flex;
  flex-direction: column;
  gap: 0.85rem;
}

/* display:flex 会盖掉 hidden 属性的默认样式，这里补回来 */
.screen[hidden] {
  display: none;
}

#screen-lobby {
  max-width: 26rem;
}

#screen-game {
  max-width: 40rem;
}

.lead {
  margin: 0 0 0.6rem;
  color: var(--fg-soft);
  font-size: 0.98rem;
  line-height: 1.6;
}

.btn {
  appearance: none;
  border: 1px solid var(--border);
  background: var(--soft);
  color: var(--fg);
  font: inherit;
  font-size: 1rem;
  font-weight: 500;
  padding: 0.95rem 1.1rem;
  border-radius: 14px;
  cursor: pointer;
  transition: transform 0.15s ease, opacity 0.15s ease, background 0.15s ease;
}

.btn:active {
  transform: scale(0.985);
}

.btn.primary {
  background: var(--accent);
  border-color: transparent;
  color: var(--on-accent);
}

.btn.ghost {
  background: transparent;
}

.row {
  display: flex;
  gap: 0.6rem;
}

.row .btn {
  flex: 0 0 auto;
}

.code-input {
  flex: 1 1 auto;
  min-width: 0;
  font: inherit;
  font-size: 1rem;
  letter-spacing: 0.22em;
  text-align: center;
  text-transform: uppercase;
  padding: 0.95rem 0.8rem;
  border: 1px solid var(--border);
  border-radius: 14px;
  background: var(--soft);
  color: var(--fg);
}

.code-input::placeholder {
  letter-spacing: normal;
  text-transform: none;
  color: var(--fg-soft);
}

.hint {
  min-height: 1.3rem;
  margin: 0.2rem 0 0;
  font-size: 0.88rem;
  color: var(--fg-soft);
}

.hint.alert {
  color: #d64a4a;
}

/* ---------- 对局中 ---------- */

.status {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-size: 0.95rem;
}

.dot {
  width: 0.75rem;
  height: 0.75rem;
  border-radius: 50%;
  background: #23262d;
  border: 1px solid rgba(0, 0, 0, 0.35);
  flex: 0 0 auto;
}

.dot.white {
  background: #fbfbfa;
  border-color: rgba(0, 0, 0, 0.2);
}

.room {
  margin-left: auto;
  font-size: 0.85rem;
  color: var(--fg-soft);
  letter-spacing: 0.08em;
}

.board-wrap {
  display: flex;
  justify-content: center;
}

canvas {
  display: block;
  border-radius: 16px;
  box-shadow: var(--shadow);
  touch-action: manipulation;
}

.actions {
  flex-wrap: wrap;
}

.actions .btn {
  flex: 1 1 auto;
}

@media (max-width: 400px) {
  main {
    padding: 1.25rem 0.9rem 1.5rem;
  }
  .btn {
    padding: 0.9rem 1rem;
  }
}